Iran has run computer simulations for a nuclear weapon that would produce over triple the explosive force of the World War 2 bomb that destroyed Hiroshima, according to a diagram obtained by the Associated Press (AP).

AP reported that the document was obtained from a 'country critical of Iran's nuclear program'. Anonymity was promised to the source, who leaked the diagram to bolster arguments that Iran's nuclear program should be stopped.

An unnamed senior diplomat confirmed that this is one of the same diagrams previously obtained by UN nuclear watchdog, the International Atomic Energy Agency (IAEA). The agency itself refused to comment.

Iran has repeatedly denied any interest in producing a nuclear weapon, saying it is producing nuclear fuel for civilian use and has refused to halt uranium enrichment, despite offers of reactor fuel from abroad. The Islamic republic has accused the US and Israel of fabricating evidence.

With both the IAEA probe and international attempts to engage Iran stalled, there are fears that Israel may opt to strike at Tehran's nuclear program. The Jewish state insists it will not tolerate a nuclear Iran.

Last year the IAEA claimed they had evidence that Iranian scientists were calculating the "nuclear explosive yield" of potential weapons. The IAEA claimed the diagrams could be dated to 2008 and 2009, although many have questioned this.

According to AP, the title of the most recent diagram includes the number '5', suggesting it is part of a series.

Nuclear expert, David Albright, told AP the diagram looks genuine but said it seems to be designed "to understand the process" rather than as part of a blueprint for an actual weapon in the making.